The biochemistry and medical significance of the flavonoids.

Plants consumed by humans contain thousands of phenolic compounds. The effects of dietary polyphenols are of great current interest due to their antioxidative and possible anticarcinogenic activities. A popular belief is that dietary polyphenols are anticarcinogens because they are antioxidants, but direct evidence for this supposition is lacking. This chapter reviews the inhibition of tumorigenesis by phenolic acids and derivatives, tea and catechins, isoflavones and soy preparations, quercetin and other flavonoids, resveratrol, and lignans as well as the mechanisms involved based on studies in vivo and in vitro. Polyphenols may inhibit carcinogenesis by affecting the molecular events in the initiation, promotion, and progression stages. Isoflavones and lignans may influence tumor formation by affecting estrogen-related activities. The bioavailability of the dietary polyphenols is discussed extensively, because the tissue levels of the effective compounds determine the biological activity. Understanding the bioavailability and blood and tissue levels of polyphenols is also important in extrapolating results from studies in cell lines to animal models and humans. Epidemiological studies concerning polyphenol consumption and human cancer risk suggest the protective effects of certain food items and polyphenols, but more studies are needed for clear-cut conclusions. Perspectives on the application of dietary polyphenols for the prevention of human cancer and possible concerns on the consumption of excessive amounts of polyphenols are discussed.

Inhibition of carcinogenesis by dietary polyphenolic compounds

Dietary agents in cancer prevention: flavonoids and isoflavonoids.

Flavonoids are polyphenolic compounds that are ubiquitously in plants. They have been shown to possess a variety of biological activities at nontoxic concentrations in organisms. The role of dietary flavonoids in cancer prevention is widely discussed. Compelling data from laboratory studies, epidemiological investigations, and human clinical trials indicate that flavonoids have important effects on cancer chemoprevention and chemotherapy. Many mechanisms of action have been identified, including carcinogen inactivation, antiproliferation, cell cycle arrest, induction of apoptosis and differentiation, inhibition of angiogenesis, antioxidation and reversal of multidrug resistance or a combination of these mechanisms. Based on these results, flavonoids may be promising anticancer agents.

Flavonoids: Promising anticancer agents

Chronic inflammation is being shown to be increasingly involved in the onset and development of several pathological disturbances such as arteriosclerosis, obesity, diabetes, neurodegenerative diseases and even cancer. Treatment for chronic inflammatory disorders has not been solved, and there is an urgent need to find new and safe anti-inflammatory compounds. Flavonoids belong to a group of natural substances occurring normally in the diet that exhibit a variety of beneficial effects on health. The anti-inflammatory properties of flavonoids have been studied recently, in order to establish and characterize their potential utility as therapeutic agents in the treatment of inflammatory diseases. Several mechanisms of action have been proposed to explain in vivo flavonoid anti-inflammatory actions, such as antioxidant activity, inhibition of eicosanoid generating enzymes or the modulation of the production of proinflammatory molecules. Recent studies have also shown that some flavonoids are modulators of proinflammatory gene expression, thus leading to the attenuation of the inflammatory response. However, much work remains to be done in order to achieve definitive conclusions about their potential usefulness. This review summarizes the known mechanisms involved in the anti-inflammatory activity of flavonoids and the implications of these effects on the protection against cancer and cardiovascular disease.

Flavonoids as anti-inflammatory agents: implications in cancer and cardiovascular disease.

Two cases of Frey's syndrome following open reduction for condylar fracture and submandibular sialoadenectomy

A case of peripheral ossifying fibroma that occurred in 17-year-old girl is presented here along with the findings of a histopathological examination. Four tumors, consisting of two larger and two smaller masses, were detected in the maxillary and mandibular alveolar bones. The larger masses were diagnosed as ossifying fibromas and the smaller ones as fibromas with no apparent calcification. The presented case, having four tumors of two different histological types, hinted at the hypothesis that transformation could occur from fibroma to ossifying fibroma. Discussion was focused in this paper to the criteria for differential diagnosis between epulis osteoplastica, cemmentifying fibroma, monostotic fibrous dysplasia, and ossifying fibroma.

Peripheral ossifying fibroma of maxilla: Report of a case

A case of primary reticulum-cell sarcoma of the lower gingiva

We report a case of an extremely small pleomorphic adenoma of the upper lip in a 62-year-old Japanese female. The tumor measuring 3×1mm, is the smallest one among the 72 Japanese cases of the lip to be reported in 53 papers published since 1969. Histopathologically, marked proliferation of epithelial and myoepithelial neoplastic cells predominated, with minimal myxomatous or chondromatous characteristics. These findings support the idea that the present tumor may represent a pleomorphic adenoma in the early stages of development.

Norichika Tatematsu

Papers

Two cases of Frey's syndrome following open reduction for condylar fracture and submandibular sialoadenectomy

Peripheral ossifying fibroma of maxilla: Report of a case

A case of primary reticulum-cell sarcoma of the lower gingiva

A case of a small pleomorphic adenoma of the upper lip

A case of desmoplastic fibroma of the maxilla